[SOLVED] Lightning dav support a bit broken

Hi All,

I have set up a second zimbra OS server, this one for a client.
On the first zimbra server (5.09 debian) I have my thunderbird client
2.0.0.16 with lightning 0.8. Everything is great! I can create/delete/edit/dismiss calender entries no problems.

On the new install, I have issues.
In lightning..
Cannot dismiss event notifications. There was a bug in 5.08 which was fixed in 5.09. But it doesnt work on this case.
Cannot edit existing events.
Cannot delete existing events.

From My laptop, which works fine with my first zimbra install, I connected to the second zimbra server and had the bad results, so I am reasonably confident it is a zimbra issue, but dont know where to look.